Eight Sudoku Myths

Clearing up some of the misunderstanding that surrounds sudoku

Introduction

Sudoku is very popular. Millions of people around the world enjoy solving sudoku puzzles. They are fun, challenging and maybe even addictive. Puzzles can be solved in a short time so people can do them when they have extra time. Within minutes beginners can start solving puzzles with little knowledge of the game. They can solve easy puzzles, then move on to harder ones as their skills improve.

There is also confusion around sudoku. Some don’t know what sudoku is or how to play it. Some believe it is really hard. Others think it requires a lot of math skills. But these myths are simply not true. Below are eight sudoku myths and explanations for why they are not true.

Myth 1: The rules are hard to understand

Rule: Arrange numbers so that all rows, columns and boxes have only one of each number from 1 to 9.

That's it. That is the only sudoku rule and as you can see it's very easy to understand. Beginners can start solving in less than a minute after reading and understanding this one rule.

Myth 2: Only “smart” people understand it

Some people think that sudoku requires solvers to be able to do very complex things to solve puzzles. However the easy ones can be solved by almost anyone. Children and novices can start with simpler versions, like 4x4 sudoku which only uses numbers 1 to 4.

Yes, there are puzzles that can be very difficult to solve. Sudoku comes in different skill levels from very easy to expert (the expert levels are often labeled diabolical, extreme, fiendish, etc.). There are even puzzles that can be too difficult for humans to do. But the easier ones don’t require degrees in rocket science or brain surgery.

The fact that there are very hard puzzles should not alarm or frighten anyone away from this fun game. There are lots of easy, medium and hard puzzles everywhere that can be easy and fun. And as skills are acquired the challenging ones don't seem so hard either.

Myth 3: Math skills are needed to understand sudoku

No math is required to solve sudoku puzzles. The numbers are merely placeholders which could be replaced by letters, colors, symbols, pictures or anything else that distinguishes nine unique items. There are sudoku puzzles that use letters (sometimes called wordoku) and others that have pictures or colors.

Sudoku is a game in which deduction, techniques and logic are used to solve puzzles but math is definitely not needed.

Myth 4: Sudoku can only be done on paper

There are a lot of apps and websites that have sudoku puzzles. There are even handheld devices specifically made for solving sudoku puzzles. There are good reasons for solving on paper and also good reasons for solving on a computer. Each way has its own pros and cons.

Solving sudoku puzzles on paper allows puzzle solving anywhere. A puzzle and a pen or pencil are all that is needed. Sudoku puzzles can be found in newspapers, on airplanes, on cruise ships and many other places. Books and magazines are available with a virtually endless supply of puzzles.

With software things can be done that can’t be done on paper like auto-filling candidates and giving hints about what the next move could be. Software can check numbers already entered and warn about mistakes. With computer apps and websites there is virtually an unlimited supply of different puzzles to be solved at all skill levels.

Myth 5: Sudoku is a game of luck so guessing is necessary

It is not necessary -- and not wise -- to guess when solving puzzles. Guessing can be disastrous because wrong numbers can easily lead to more wrong numbers. It can be difficult to determine which numbers are correct and which ones are not to undo mistakes.

Hence guessing is not at all recommended! To avoid confusion it should never be done. Puzzles can and should only be solved by placing correct numbers as they are found.

There is always enough information in a puzzle with the givens (numbers placed at the beginning) to find all of the numbers using logic, deduction or other solving techniques. This is in fact what makes sudoku exciting and gives players a sense of accomplishment.

Myth 6: Some sudoku puzzles can’t be solved

It is always possible to solve sudoku puzzles. Most are designed for humans to be able to solve using logic, deduction and learned techniques. They are typically in the range of easy, medium, hard and expert.

There are puzzles that are nearly impossible for a human to solve but they are the exception and there aren’t very many of them. One that is very difficult is called AI Escargot.

A “well-formed” sudoku puzzle is one that only has one solution. The vast majority of puzzles available are well-formed. It is possible to find puzzles that are not well-formed but they are mistakes or not designed well. Sudoku puzzles available to solve imply that they are well-formed.

Myth 7: Sudoku was invented by the Japanese

The puzzle we know today wasn’t invented until late in the 20th century in the United States, not in Japan.

Sudoku’s roots go way back. Here is a quick history.

In 2000 BC the Chinese created the “Magic Square” -- a 3x3 array of numbers which have the same sum for all rows, columns and the two diagonals.

Leonhard Euler created the “Latin Square” in the 1780s in Switzerland. It is like a magic square but the sum rule was taken away so that other symbols could be used in addition to numbers. Each row and column contain unique numbers or characters.

French newspapers from the 1890s to the 1920s carried Latin Square puzzles with 9x9 grids using the numbers 1 through 9.

American Howard Garnes invented sudoku in the 1970s. He took the French puzzle and added 3x3 boxes to the 9x9 grid. The 3x3 boxes must also hold numbers 1 through 9. This made the puzzle more challenging and interesting. Dell carried Garnes’ puzzles (called “Number Place”) in their magazines.

Japanese company Nikoli discovered the Dell puzzles. They changed them slightly and published them in “The Nikolist.” They were later called 'Suji wa dokushin ni kagiru' which means “the digits must remain single.” The name was shortened to sudoku.

In early 2000 Wayne Gould created a computer program to generate puzzles and published them in “The Times” of London. Puzzles also appeared in an American newspaper earlier. From these sources sudoku quickly spread and became popular worldwide. The name sudoku stuck.

Myth 8: Sudoku is not fun

One need only to try it to find sudoku is fun. It is not only fun but can be relaxing and stimulating at the same time. The real fun of sudoku is solving more difficult puzzles which brings with it a sense of satisfaction and accomplishment.

Summary

If you don’t know how to solve sudoku puzzles or haven’t ever tried, grab an easy puzzle and try solving it. You only need to remember that each row, column and box can only have one of each number from 1 to 9.